Zeolite is used as a catalyst, a catalyst carrier, an adsorbing material, or the like. In addition, a zeolite membrane element where a membrane is formed on a surface of a porous substrate made of metal or ceramic has been used as a gas separation membrane or a pervaporation membrane by the use of the molecular sieving function of zeolite.
In zeolite, many kinds of crystal structure such as LTA, MFI, MOR, AFI, FER, FAU, DDR, and the like are present. Among them, DDR (Deca-Dodecasil 3R) is a crystal containing silica as the main component, and it is known that the pores are formed of a polyhedron containing an oxygen eight-membered ring and that the pore size of the oxygen eight-membered ring is 4.4×3.6 angstrom (see W. M. Meier, D. H. Olson, Ch. Baerlocher, Atlas of zeolite structure types, Elsevier (1996)).
The DDR zeolite has relatively small pore size among zeolite and has a possibility of application as a molecular sieve for low molecular gas such as carbon dioxide (CO2), methane (CH4), and ethane (C2H6).
In addition, as a method for manufacturing a DDR zeolite, there is disclosed a manufacturing method capable of manufacturing a dense DDR zeolite membrane in a short period of time by specifying the proportion of the contents of 1-adamanthanamine, silica, water, and ethylenediamine in the raw material solution (see, e.g., Patent Document 1). This method exhibits an excellent effect in being able to manufacture a dense DDR zeolite membrane in a short period of time.
A DDR zeolite membrane element, where a DDR zeolite membrane is formed on a surface of a porous substrate, may have a structure where a seal portion is formed by applying a seal material in a predetermined portion on a surface of the porous substrate to inhibit inflow and outflow of a target fluid from the seal portion.
Generally, as a sealing material of a zeolite membrane, a resin such as a silicone resin, a polyimide resin, or an epoxy resin, or a glass is used. Though it is required to change the material in accordance with the usage environment (temperature, pressure, atmosphere, and the like), in the case of using a membrane at relatively high temperature or in an atmosphere where it is exposed to an organic solvent, there have been proposed a method where a filler is mixed and a method where a mechanically sealing structure is employed (see, e.g., Patent Documents 2, 3).    Patent Document 1: JP-A-2003-159518    Patent Document 2: JP-A-2000-109690    Patent Document 3: JP-A-2007-50322